The evaluation of the shade of a tooth can be performed visually by a dentist. It is performed, for example, by comparing a tooth to be replaced with a number of reference teeth of a dental shade guide. There are several types of dental shade guides. Generally, dental shade guides have various color ranges, and for each color range, a set of reference teeth with various color saturations.
Visual evaluation allows the dental specialist to take into account the special features of each tooth, and especially any inhomogeneities. However, and despite standardized lighting, the visual evaluation method, remains a subjective method. In particular errors can result from faulty color perception or the practitioner's visual fatigue.
A more objective evaluation can be performed using a colorimeter. The colorimeter analyzes the spectral response of a tooth in a wide band of excitation light. It can be linked to suitable visualization software, to prepare a shade map of a tooth. The shade map is then displayed on a control screen. A colorimeter of this type is commercially available, for example the Shade Scan make.